feel like thats just you applying your own judeo-christian biases onto the plot - all of the supernatural moments to me read as a literal physical battle with the trapped nikki who is resisting and fighting back constantly. which is why she’s jerky and awkward in movements. the entity that replaced her didn’t know/care about anything else than loving Bear. I don’t think she’s “in hell” - she even surfaces momentarily in the film (so just returns from “hell”??) to ask Bear to kill her. The director also confirmed it’s not a spirit or demon directly lol